1. Field of the Invention
This invention relates to footwear and more particularly relates to open-heeled foot apparel.
2. Description of the Related Art
Open-heeled or backless footwear such as sandals, flip-flops, clogs, or the like are a popular clothing item worn by people of all ages in many areas around the world. Though popular as footwear, open-heeled foot apparel often causes discomfort to the wearer because the heel pad of the foot-receiving platform typically does not line up accurately with the actual contact area of the heel. Particularly when the foot is raised, such as when walking, the foot-receiving platform tends to swing toward the outer edge of the foot. As the foot comes down on the foot-receiving platform, the heel tends to contact the platform near the inner edge, which provides minimal support to the foot and often creates a worn heel-contact area off-centered from the available heel pad.
FIGS. 1A-1B illustrate one embodiment of a flip-flop 100 similar to those currently available on the market. Flip-flops 100 typically are a backless sandal held to the foot by a thong between the big toe and the second toe. The flip-flop 100 commonly comprises a platform 110, a heel pad 112, and a retaining covering 114 such as straps 114.
In certain embodiments, the platform 110 is made of a flat foam rubber with straps 114 attached at three contact points 116 and is generally shaped to contour the foot. Alternatively, flip-flops 100 and/or open-heeled foot apparel may be made from a variety of materials such as leather, wood, plastic, elastomer and the like. Some backless sandals even include a spiked heel and/or an inclined platform 110. The retaining covering 114 may comprise a single strap 114 or an intricate infrastructure. Those of skill in the art will recognize that flip-flops 100 and other backless footwear may be configured from a variety of materials. In addition, the platform 110, heel pad 112, and retaining covering 114 may be configured in a variety of styles and/or arrangements.
The retaining covering 114 may facilitate defining a centerline 118 that divides the area within the retaining covering 114 approximately equally. In the depicted embodiment, the centerline 118 passes through an approximate center of the platform 110 beginning from a midpoint 120 located between contact points 116b and 116c. 
The heel pad 112 may include the lower portion of the platform 110. A geometric center point 122 may be identified for the heel pad 112. A line 124 passing through the center point 122 and the midpoint 120 may facilitate defining an angle 126. In certain embodiments, the angle 126 may represent the natural curve in the foot. Generally, the angle 126 may be insubstantial and may be about 180 degrees.
FIG. 1B illustrates an actual heel contact area 128 that has a center point 129. The heel contact area 128 is typically located near the inner edge 130 of the flip-flop 100. As the platform 110 swings during movement, the heel makes contact near the edge 130 of the platform 110, which offers a diminished amount of support to the heel. The inner edge 130 tends to break down quicker than the outer edge 132, creating an uneven, sloped platform 110. The user typically experiences discomfort as the heel pad 112 wears unevenly. In addition, the outer edge 132 of the flip-flop 100 typically boasts an excess of unused platform material. The excess material may annoy the user.
In shoes or footwear that have a heel retaining device or back, the problem is somewhat mitigated. In such an embodiment, the platform 110 and/or sole of the shoe is generally bound to the foot and does not typically swing, as is common with open-heeled footwear. As a result, the foot-receiving platform 110 generally remains in line with the foot, particularly the heel. Yet the demand for open-heeled footwear continues to remain high.
From the foregoing discussion, it should be apparent that a need exists for an open-heeled article of foot apparel that anticipates the swinging movement of the foot-receiving platform and positions the center of the heel pad where the heel of the foot is most likely to strike. Beneficially, such an article of foot apparel would provide popular open-heeled footwear that is comfortable to wear and is long-lasting. Providing a heel pad centered where the heel of the foot is most likely to strike would provide better heel support to the user and would potentially increase the life of the foot apparel.